import json
from enum import Enum
from datetime import datetime, timezone
from .status import Status
from .credential import Credential

class Role(Enum):
    ADMIN = "admin"
    MEMBER = "member"
    GUEST = "guest"

class Grant:
    def __init__(
        self,
        grantor: str,
        expires_at: datetime,
        granted_at: datetime = None,
        last_used_at: datetime = None,
        status: Status = Status.ENABLED
    ):
        self.grantor = grantor
        self.granted_at = granted_at or datetime.now(timezone.utc)
        self.expires_at = expires_at
        self.last_used_at = last_used_at
        self.status = status

    def to_dict(self) -> dict:
        return {
            "grantor": self.grantor,
            "granted_at": self.granted_at.isoformat(),
            "expires_at": self.expires_at.isoformat(),
            "last_used_at": self.last_used_at.isoformat() if self.last_used_at else None,
            "status": self.status.value
        }

    @classmethod
    def from_dict(cls, data: dict):
        return cls(
            grantor=data.get("grantor", ""),
            expires_at=datetime.fromisoformat(data["expires_at"].replace("Z", "+00:00")),
            granted_at=datetime.fromisoformat(data["granted_at"].replace("Z", "+00:00")) if data.get("granted_at") else None,
            last_used_at=datetime.fromisoformat(data["last_used_at"].replace("Z", "+00:00")) if data.get("last_used_at") else None,
            status=Status(data.get("status", Status.ENABLED))
        )

class User:
    def __init__(
        self,
        id: str,
        username: str,
        fullname: str,
        role: Role = Role.GUEST,
        credentials: Credential = None,
        grants: dict[str, Grant] = None,
        status: Status = Status.ENABLED
    ):
        self.id = id
        self.username = username
        self.fullname = fullname
        self.role = role if isinstance(role, Role) else Role(role)
        self.credentials = credentials or Credential("", "")
        self.grants = grants or {}
        self.status = status if isinstance(status, Status) else Status(status)

    def to_dict(self) -> dict:
        return {
            "id": self.id,
            "username": self.username,
            "fullname": self.fullname,
            "role": self.role.value,
            "credentials": self.credentials.to_dict(),
            "grants": {gate: grant.to_dict() for gate, grant in self.grants.items()},
            "status": self.status.value
        }

    @classmethod
    def from_dict(cls, id: str, data: dict):
        credentials = Credential.from_dict(data.get("credentials", {}))
        grants = {gate: Grant.from_dict(grant) for gate, grant in data.get("grants", {}).items()}
        return cls(
            id=id,
            username=data.get("username", ""),
            fullname=data.get("fullname", ""),
            role=Role(data.get("role", Role.GUEST)),
            credentials=credentials,
            grants=grants,
            status=Status(data.get("status", Status.ENABLED))
        )

class Users:
    def __init__(self, json_path: str = "./data/users.json"):
        self._json_path = json_path
        self._users: dict[str, User] = self._load_users()

    def _load_users(self) -> dict[str, User]:
        try:
            with open(self._json_path, "r") as f:
                data = json.load(f)
            return {uid: User.from_dict(uid, info) for uid, info in data.items()}
        except Exception:
            return {}

    def _save_users(self) -> None:
        with open(self._json_path, "w") as f:
            json.dump({uid: user.to_dict() for uid, user in self._users.items()}, f, indent=2)

    def update_user(self, id: str, username: str, fullname: str) -> bool:
        if not id or not username or not fullname:
            return False
        if id in self._users:
            self._users[id].username = username
            self._users[id].fullname = fullname
        else:
            self._users[id] = User(id, username, fullname)
        self._save_users()
        return True

    def get_username(self, id: str) -> str | None:
        return self._users[id].username if id in self._users else None

    def get_fullname(self, id: str) -> str | None:
        return self._users[id].fullname if id in self._users else None

    def get_status(self, id: str) -> Status:
        return self._users[id].status if id in self._users else Status.DISABLED

    def get_role(self, id: str) -> Role:
        return self._users[id].role if id in self._users else Role.GUEST

    def get_credentials(self, id: str) -> Credential | None:
        return self._users[id].credentials if id in self._users else None

    def set_credentials(self, id: str, credentials: Credential) -> bool:
        if id in self._users:
            self._users[id].credentials = credentials
            self._save_users()
            return True
        return False

    def can_open_gate(self, id: str, gate: str) -> bool:
        user = self._users.get(id)
        if not user or user.status != Status.ENABLED:
            return False
        if user.role == Role.ADMIN or user.role == Role.MEMBER:
            return True
        grant = user.grants.get(gate)
        if not grant or grant.status != Status.ENABLED:
            return False
        if grant.expires_at <= datetime.now(timezone.utc):
            return False
        return True

    def has_grants(self, id: str) -> bool:
        user = self._users.get(id)
        if not user or user.status != Status.ENABLED:
            return False
        if user.role == Role.ADMIN or user.role == Role.MEMBER:
            return True
        return any(grant.status == Status.ENABLED and grant.expires_at > datetime.now(timezone.utc) for grant in user.grants.values())

    def get_grantor(self, id: str, gate: str) -> str | None:
        user = self._users.get(id)
        if not user:
            return None
        grant = user.grants.get(gate)
        return grant.grantor if grant else None

    def get_admins(self) -> list[str]:
        return [uid for uid, user in self._users.items() if user.role == Role.ADMIN]

    def grant_access(self, id: str, gate: str, expires_at: datetime, grantor_id: str) -> bool:
        user = self._users.get(id)
        if not user:
            return False
        user.grants[gate] = Grant(grantor_id, expires_at)
        self._save_users()
        return True

    def revoke_access(self, id: str, gate: str) -> bool:
        user = self._users.get(id)
        if not user:
            return False
        if gate in user.grants:
            del user.grants[gate]
            self._save_users()
            return True
        return False

    def update_grant_last_used(self, user_id: str, gate: str) -> bool:
        user = self._users.get(user_id)
        if not user:
            return False
        grant = user.grants.get(gate)
        if not grant:
            return False
        grant.last_used_at = datetime.now(timezone.utc)
        self._save_users()
        return True